There is something magical about wood fires, and people are often tempted to put them into their houses. In writing on low energy building, I haven't really talked about wood burning stoves. People sometimes ask how you can fit a wood burning stove in a low energy building, but the question you first need to answer is: why do you want a wood burning stove?
Before you get one for your house, and especially before you plan to build a new house around a wood burner, you should check that you meet at least four or five of these seven criteria. You don't have to meet all the criteria, and in fact some of them may contradict each other. But you should meet most of them.
1. You have a sustainable source of wood.
Perhaps you live in a forest, or a relative has an orchard, or you live next to a timber yard, or you just inherited a derelict warehouse with a large collection of broken pallets. If you don't know where your wood is going to come from, then you will need to buy it. You may have thought that wood grows on trees. In fact wood does grow on trees, but those trees grow on land, and that land usually belongs to someone. The trees also play a major role in creating habitat for wildlife, and are acting as a sink of atmospheric carbon and a source of oxygen.Well-managed forest can provide better habitat for wildlife and can provide more effective carbon sinks, but burning wood will send some of the carbon that has been stored over the last decades or centuries straight back into the atmosphere. Even if the forests are well managed, burning the wood that grows there may not be the best use of it. If left on the forest floor, wood can provide excellent nutrition for the forest and habitat for some of the diverse life there.
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| Not really firewood! |
So wood may not be the best fuel for your house in terms of economics or ecology.
Or it may be the best thing in terms of economics and ecology.
I don't know the answer, but if you're thinking of using wood, please find out!
2. You like chopping and storing wood, making fires and cleaning stoves and chimneys.
Having a wood burning stove is a lifestyle choice. That's another way of saying that it will take more time, cost more money and may be worse than the alternatives in various other ways. Wood needs to be chopped and stored where it will stay long enough to dry out, but not too long in the same place where it will attract insects and other undesirables. If you only occasionally want to burn stuff, it may be better to go camping. There are some great campsites that allow you to have a fire!3. You have no neighbours.
You may be planning to go off-grid, which is a great idea if you live away from civilisation, and this may go hand-in-hand with the first criteria. If you are in a residential area, your neighbours may not appreciate smoke getting into their washing. This article in the Huffington Post suggested that the most efficient wood-burning stove will put out the same levels of pollution as 18 diesel cars. Would you like a fleet of cars driving around your neighbourhood?4. You are going to get the most efficient model available, with a properly installed chimney.
Benjamin Franklin did make significant improvements to stove design back in the 1700s, but even in the 1800s wood burning stoves were only 30% efficient. They sent out particles at levels that would be illegal today, and allowed creosote to build up in chimneys, creating a fire hazard.Things have got better since the 1800s but even the most efficient wood burning stove will only burn wood at around 80% efficiency.
5. Your wood burning stove can run on pellets.
Part of the problem is the wood itself. It seems that wood was not designed with burning efficiency as the first priority. Wood pellets provide a more even fuel and allow higher efficiency. Many wood pellets are currently made from sawdust or waste wood products. There are also pellets made from grass cuttings. If demand increases, wood will be cut directly to make pellets, which may remove some of the supply-end energy efficiency, but they will still burn cleaner.More efficiency means more of the wood is turned into water and carbon dioxide, rather than other more polluting substances or unburnt particles or residues. So more efficiency means less pollution and less cleaning. Air quality is an issue in many places, and burning wood certainly does not improve it.
You may consider a dedicated pellet burner, which will be easier to clean, and easier to use since it feeds the pellets via a hopper and may be controlled by a thermostat and a timer. It will probably be cheaper to install since the unit usually has a heat exchanger so a simpler chimney can be used. If you're still wondering about the answer to question 1, wood pellets could be your answer.
6. You are only going to light your stove a few times a year, and are mostly getting the stove because it will look nice in your living room.
If you're thinking of adding a wood-burning stove to a ready-built house, you may not need to worry about this question. But if you're building new, I recommend your first priority to be insulation rather than burning wood.
Depending on your climate, if you have a well-insulated house, most wood burning stoves will make your house overheat, except on the coldest few days of the year. Your well-insulated house should also be airtight, and this may not be sensible if you are burning wood.
7. You know that if burning wood was the best way to stay warm, everyone would still be using it.
Most of us no longer send telegrams, spin yarn on spinning wheels, or nip down to the local smithy to get a horse shoe fixed. We stopped doing these things because of new technology that is cheaper and more time-effective. Burning wood will likely be more expensive and more time consuming than the options. Wood was our first fuel source; if wood produced more energy than fossil fuel reserves, we would never have deforested vast areas of the planet to mine coal or pipe oil and gas.There is an old saying: if God had not intended us to burn wood, he would never have invented matches. Actually that's not an old saying at all, I just made it up. But there is something natural and wholesome about a wood fire.
Burning wood is better for the carbon cycle than burning fossil fuels. However, it may be better to burn nothing. If you want to avoid or reduce fossil fuel use, the first thing you need to do is improve your insulation. Then it may be better to electrify your heating, which allows you to use renewable energy.
If you see yourself as an eco-warrior and see fire as one of your weapons against the machine, then be aware of the possibility that with fire you are fighting against ecology rather than fighting for it! I know in the situation we are in, the choice between wood burning or electrified heating may be something like choosing between a bicycle and a skateboard as you prepare to go over a waterfall.
I don't have all the answers, but I do have the questions!
So how did you score? If you answered yes to most of them, you're good to go. If not, I recommend looking into heat pumps, either in self-contained air conditioning units, or producing hot water for radiators or underfloor piping.
Remember, taken in moderation, wood burning stoves can form part of a calorie-controlled energy diet for your planet!
References:
If you want to get a stove, go to Michael's Stove Shop.
More details from the US Office of Energy Efficiency and Renewable Energy: Choosing and Installing Wood- and Pellet-Burning Appliances
Chapter on Energy Return on Investment (EROI) of Different Wood Products by Zdravko Pandur, Marijan Šušnjar, Marko Zorić, Hrvoje Nevečerel and Dubravko Horvat (2015)
